The aforementioned parent application, Ser. No. 337,591 describes and claims an improved vented wound dressing having a base sheet for contacting the skin of the patient, the base sheet having an opening for placement over the wound. The dressing has a cover sheet secured to the base sheet having vent means for providing controlled leakage of fluid along a path from the wound through the opening in the base sheet while reducing evaporation through the opening and thereby helping to insure a moist environment when excess wound fluid is removed from the wound.
In accordance with the various embodiments disclosed in the aforementioned application, the vent cover sheet may be substantially planar or it may be raised or corrugated.
The flat cover sheets will in general provide entirely satisfactory leakage for a period of time. However, in time they have a tendency to become sealed by drying serum or wound exudate. Accordingly, such a cover design is not optimal for permitting controlled leakage in dressings that are expected to be retained in place and to continue leaking for several days or longer.
Raised or corrugated vent cover sheets, on the other hand, will maintain reliable leakage for appreciably longer periods. However, they tend to be difficult to manufacture and moreover, are not as esthetically pleasing.
The task of this invention, simply stated, is to provide an improved cover sheet which is characterized as being easy to manufacture, esthetically pleasing and which will provide reliable controlled leakage for an extended period of time.